The present invention pertains to colleting devices, and in particular, to a spindle having means operative thereof for releasably engaging the inner surface of a workpiece and rotating the workpiece thus engaged in vacuum deposition environments.
The use of cam-like devices to engage and lock a workpiece to a rotating shaft is well known. Once such device comprises a cylindrical plug, keyed in place to prevent independent rotation, sliding within a hole bored through a sleeve. The plug has a conical head which rides within a counterbore in one end of the sleeve. The largest diameter of the conical head is slightly less than the diameter of the counterbore. Four pins slide freely within four equally-spaced holes drilled radially through the walls of the sleeve into the counterbore. A clevis pin is threaded through the center of the plug and extends the length of the sleeve. An operating lever with a forked end fits over and is coupled to the clevis pin and bears against the end of the sleeve with smaller diameter bore. A cam-like curvature is formed at the connecting end of the lever with the cam radius gradually increasing through ninety degrees of rotation.
To lock the sleeve within the bearing hole in a workpiece, the operating lever is pivoted through ninety degrees. This action draws the conical head of the plug into the counterbore and into contact with the four pins extending radially through the wall of the sleeve. As the plug is drawn into the counterbore, the pins are forced radially outward and into a receiving groove in the bearing surface of the workpiece thereby locking the workpiece to the sleeve.
U.S. Pat. No 4,398,733, issued to Thomas C. Mosley, Jr., on May 13, 1981, discloses a jawed lathe chuck having means selectively operative for engaging either the outer surface of a workpiece or the inner surface of a workpiece. The chuck comprises a hub rotatably journalled in a jaw carrier, and the latter rotatable journalled in a body. The carrier pivotably mounts a plurality of jaws having camming surfaces, and drive pins upstanding from the hub and body slideably engage the camming surfaces to move the jaws outwardly, to engage the inner surface of a workpiece, or inwardly, to engage the outer surface of a workpiece. A screw carried in the jaw carrier is movable into the hub, to lock the hub and jaw carrier together, and movable into the body, to lock the body and the jaw carrier together to prevent relative rotation between the hub and the jaw carrier or between the jaw carrier and the body.
U.S. Pat. No. issued to Robert L. Shrader on Jan. 11, 1977, discloses an assembly for lifting a substrate holder from its carrier platform and rotating the holder in a vacuum chamber during a substrate coating process. The assembly comprises essentially a main assembly that is reciprocally movable in a vertical direction by an actuating piston and a sub-assembly that is embodied in and movable with the main assembly. The sub-assembly comprises a permanent magnet and a second or auxiliary actuating piston for independently and reciprocally moving the magnet in a vertical direction with respect to the main assembly. When the magnet and substance holder are coupled, actuation of the main piston lifts the entire assembly together with the substrate holder, clear of the carrier platform.
For rotating the coupled magnet and holder during the coating process, the magnet which is independently rotatable within the assembly about its vertical axis, is connected by a spring belt transmission to exterior motive means through a suitable seal in the coating chamber wall.
A principle concern in high vacuum, elevated temperature, thick or thin film deposition systems is to minimize the sources of particles within the deposition chambers which contaminate the deposition process itself. Typically, a major source of particles result from actuation or frictional engagement of metal parts. Further, in the production of certain deposited-film parts, such as disc memory media, magnetic contamination cannot be tolerated.
In accordance with the present invention, a high vacuum sputtering chamber is provided with a horizontal spindle housing or the like, in which a colleting and spindle assembly for lifting and rotating a substrate mounting chassis is mounted. Lifting and clamping action is accomplished utilizing rolling contact between surfaces produced by rotating a minor shaft with an eccentrically mounted bearing within and relative to a major shaft. As the minor shaft rotates relative to the major shaft, the distance between the major shaft centerline and the eccentric bearing centerline is varied.
The apparatus in accordance with the present invention comprises a plunger shaft mounted within and coaxial to a spindle shaft. The plunger shaft inclues a bearing eccentrically mounted on one end of the shaft protruding from the plunger shaft beyond the spindle tip. The spindle shaft is rotationally mounted horizontally in the spindle housing with the spindle tip protruding into the vacuum chamber through a bellows assembly fixably attached to the exterior of the vacuum chamber. The spindle shaft is reciprocally movable transversely to the chamber wall by a first pneumatically-actuated piston for releasably engaging a hub in the center of the substrate mounting chassis. A second pneumatically-actuated piston mounted on the rear end of the spindle shaft drives an internally mounted high helix screw which is prevented from rotating relative to the spindle shaft causing a high helix nut to rotate relative to the spindle shaft. The rotational motion of the helix nut is coupled to the plunger shaft causing it to rotate relative to the spindle shaft.
To rotate the substrate mounting chassis within the vacuum chamber, the spindle tip is first inserted in the substrate mounting chassis hub by activation of the first piston. Activation of the second piston causes the plunger shaft to rotate bringing the eccentric bearing into contact with the inner surface of the hub. Further rotation of the plunger shaft lifts the substrate mounting chassis free of a chassis transport platform. Because the plunger shaft centerline is also eccentric to the spindle shaft centerline further rotation of the plunger shaft positions the chassis such that the hub horizontal axis is coincident with the spindle centerline. The chassis is locked in this position by the clamping action resulting from contact by the inner surface of the chassis hub with a locating pad protruding from the spindle tip. The spindle shaft now acts as a drive shaft to impart rotational motion to the chassis provided by an external source.